The present invention relates to a regulatable drive for a motor vehicle component, in particular for a water pump in a motor vehicle.
Regulatable drives for use in a motor vehicle are known and serve, for example, for regulating the water pump rotational speed in order to regulate the volume flow of the cooling medium for an internal combustion engine as a function of the heat energy to be discharged. The couplings used in the prior art present the problem, inter alia, that a reliable rotational speed setting is problematic because of the difficult torque transmission or the regulating range is relatively small. This does not permit an economically appropriate use in a motor vehicle, in particular for vehicles employing an internal combustion engine.
Furthermore, in known prior art drives, the output rotational speed is regulated as a function of the degree of filling of a coupling with shearing fluid, creating, inter alia, the risk of an uncontrolled standstill of the drive in the case of a decreasing oil quantity. The result of this, for example, in the drive of a water pump in a motor vehicle, is that the heat generated by the internal combustion engine is not discharged sufficiently and there is the risk of engine overheating.
There are also similar disadvantages in what are known as hysteresis couplings which, however, additionally have problems of regulation in low torque ranges, so that, here too, there is the risk that an uncontrolled standstill of the coupling drive may occur.